You may change the Massachusetts amount to 0. It will still calculate your MA income based on your income earned everywhere, so it should then calculate correctly. In fact, if no MA tax was withheld, you may delete the MA line entirely from your W-2.
The other question is why is California income tax being withheld from your pay? Even if your employer was based in California, if you are telecommuting from MA, you should not be paying California taxes. See Scenario 2 under Income sourcing for nonresidents temporarily relocated to California, and filing and paying California income taxes during COVID-19 for a similar situation.
You only pay California taxes if the income is sourced in that state, meaning you were physically present in California. If not, you should not allocate any of your wages to California and should get an entire refund of the amount of California taxes withheld. Of course, you would owe Massachusetts taxes on the same wages, but Massachusetts generally taxes at a lower rate than California so you should come out ahead.
If you are telecommuting from MA, you will want to notify your employer to start withholding the proper state's taxes. Once they get it right, you should not have to file a CA state return at all.
@happy_tax_jian
